I would like to trace built-in append/3 in SWI-Prolog, but am getting the result immediately and cannot see what is going on in the middle.
Is there anything I have to do to enable trace for append?
?- trace .
true.
[trace] ?- append([a,b,c], [[],[2,3], b], X).
X = [a, b, c, [], [2, 3], b].